How to diagnose a motor using a sheet of paper - Rossiyskaya Gazeta

In garages, engine operation is checked using electronic equipment connected to the central bus. There is a way to carry out mini-diagnostics on your own, without the use of special devices.

To do this, you only need an ordinary sheet of white paper. Before starting the check, you need to warm up the engine well, since in a cold state the nature of the exhaust will be different, writes… It will be optimal to carry out diagnostics after a short trip: 15 minutes will be enough, the coolant temperature should reach 50-90 degrees.

Next, you need to bring a sheet of paper to the exhaust pipe and hold it for several minutes. If it is sucked into the pipe, then this indicates back pressure. This happens when the exhaust gases do not completely pass through the pipe due to its limited throughput. They are then sucked back in at the start of the intake stroke.

Burnt valves may be the cause. Another option is problems with the Exhaust Gas Recirculation (EGR) system, whose task is to transfer some of the exhaust to the intake manifold in order to briefly reduce combustion efficiency. Breakage may also be in the timing mechanism, but most often the matter is in clogging and burning of the catalyst cells.

Normally, the paper should fluctuate evenly: no pops, blowing to the side, rhythm failures should be observed. If it happens otherwise, most likely there is a problem with the ignition. Jerks occur due to uneven feed of the mixture. It is worth checking the spark plugs and coils.

After a couple of minutes, you need to examine the sheet of paper. Normally, it should be clean, maximum – covered with a small amount of moisture interspersed with soot. But if brown oily stains appear on the paper, then there is a possibility of malfunction.

The heated oil enters the exhaust through damage in the cylinder walls, so they should be inspected for scoring. It so happens that serviceable engines emit oil through the exhaust pipe. This is often characteristic of turbocharged units. However, this does not happen at idle speed of the engine, but during active gas addition.

Light, oily streaks on a piece of paper indicate that the exhaust contains antifreeze vapors. This can happen if the cylinder block gasket is burnt out. The exhaust will then resemble white steam. An urgent repair is needed, since the lubricant diluted with antifreeze loses its properties. Coolant leakage can also occur if there is a problem with the cylinder head.

If the marks on the sheet of paper resemble a soot coating, then, most likely, there is a violation of the mixture formation system. Broken sensors affecting injection may be to blame. In this case, the fuel does not completely burn out, gasoline vapors leave a black sediment on heated surfaces. Normal engine operation is impaired. On the dashboard, with such a breakdown, the Check Engine lamp lights up. But if you are checking the engine when buying a used car, then you need to know: this signal can be suppressed in the settings. This is what unscrupulous sellers use.

For any of the described results of self-diagnosis of the engine, it is worth visiting a car repair shop and repeating the check already there. If any of the above problems come to light when buying a used car, then it is better to refrain from such a transaction.

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